Technical Field
The present invention generally relates to non-planar semiconductor structures with epitaxial structures on top surfaces of raised semiconductor structures. More specifically, the present invention relates to such structures with mixed n-and-p-type raised structures, and increasing the surface area of the epitaxial structures without adding additional epitaxial material.
Background Information
With the ever-shrinking sizes of semiconductor devices, creativity in design has allowed the decrease in size to continue. For example, non-planar devices with raised semiconductor structures (e.g., “fins”) were an important breakthrough, while the inclusion of epitaxial semiconductor structures at the top surface of the raised structures further extended the breakthrough of non-planar devices. Complicating the situation is the inclusion of mixed n-and-p-type raised structures on the same substrate, requiring different epitaxial materials. As dimensions continue their downward march, the real-world sub-structures produced stray farther and farther from the ideal dimensions and/or shape. For example, the raised structures have a tapered shape, getting gradually larger from tip to base, the tip being the location for the epitaxial structure. In turn, the epitaxial structure is smaller, the surface area of which largely determines current throughput, and, hence, a key performance contributor.
Therefore, a need continues to exist for a way to improve semiconductor performance, and, in particular, current throughput, bearing in mind existing design constraints with regard to the total height of the raised structure with epitaxial structure on top.